Elastic fluid surface condenser



April 19, 1938. B. P. couLsoN, JR 2,114,873

ELASTIC FLUID SURFACE CONDENSER Filed May 16, 1955 Fig.3

Inventor". Bevis F CoLUsovm, J

is AttOTTjey.

' Patented Apr. 19, 1938 ELASTIG FLUID SURFACE CONDENSER,

Bevis P. Coulson, J12, Schenectady, N. Y., assignor to General ElectricCompany, a corporation of New York Application May 16, 1935, Serial No.21,891

3' Claims.

The present application is a continuation in part of my applicationSerial No. 712,538, filed February 23, 1934, relating to elastic fluidsurface condensers, particul-arly. mercury vapor '5 condenser andcondenser boilers, although it. is not necessarily limited thereto. Theinvention is of special importance in connection with surface typemercury condenser boilers in which mercury vapor is condensed by amedium such 10 as water which in turn is evaporated.

Vapor exhausted by elastic fluid turbines contains air and othernon-condensable gases leaking past packings into theinterior of turbinesexhausting into condensers. The amount of such 15 gases is oftenconsiderably increased dueto air leaking from theatmosphere into thecondenser. These .non-condensable gases in surface cond'ensers reducethe heat transfer from the vapor throughthe tubes to the cooling mediumby forming blankets on the tubes, an eifect known as blanketing of thetubes. To overcome this drawback, it is necessary to provide means forremoving or extracting, non-condensable gases from the condensers. 7

One object of my invention is to provide an improved construction andarrangement of mercury condensers and the like whereby the air and othernon-condensable gases contained in the mercury vapor or like elasticfluid to be condensed are readily removed and the efficiency of thecondenser thereby substantially increased.

Another object of my invention is to provide an improved arrangement ofcondensers in which the ,floW of non-condensable gases through theconduit for discharging condensate is substantially eliminated.

- This is accomplished in accordance with my invention by the provisionof means for extracting the non-condensable gases at the region orregions where the final condensation takes place.

I have found that the relative amount of air or other non-condensablegases contained'in the mercury vapor increases with increasingcondensation and reaches a maximum in those regions 45 of the condenserin which the final condensation takes place. Therefore, I provideair-extracting means which may be in the form of a tube or tubes with aplurality of openings located at points of minimum heat concentrationdue. to

50 the blanketing of the condenser tubes by the non-condensable gases.

The second object of my invention is accomplished by the provision ofmeans reducing the flowaofnon-condensablestowards the outlet for 55 thecondensate;

For a better understanding of what I believe to be novel and myinvention, attention is directed to the following description and theclaims appended theretoin connection with the accompanying drawingwhichforms a part of my specification. v

In the drawing, Fig. 1 is a sectional view of a condenser embodying myinvention; Fig. 2 is a cross-section along line 22 of Fig. 1; Fig. 3 isa sectional view of a modification of my invention; and Fig. 4 is asectional view, partly broken away of another modification of myinvention.

The surface condenser shown by way of example in Fig. 1 is a condenserboiler for con- '15 densing mercury vapor and evaporating water of thetype in which a single bank of tubes communicating with a header or tankfor receiving coolingmedium is provided. It comprises a lower tank Hiand an upper tank or header H having '2 flanged portions united by boltsl2. Depending from the upper tank H are a plurality of deadend tubes l3communicating with the upper tank. The lower tank It! has a flangedopening M for receiving mercury vapor to be condensed. A sump l5 havinga discharge conduit it for mercury liquid is connected to the bottom ofthe lower tank. The upper tank II has an inlet conduit If for conductingwater to the tank and an outlet conduit l8 for discharging steam. Duringoperation, mercury vapor is passed across the outer surfaces of thedepending tubes I3 whereby its heat content is transferred to the watercontained in the tubes l3, effecting condensation of the mercury andevaporation of the water. The mercury condensate collects in the sump I5and is discharged through. the conduit Hi. The steam generated in thedepending tubes l3 flows into the upper tank I l and is dischargedthrough the conduit IS. The direction of flow of 4D the mercury vapor isindicated by arrows in Fig.

2. The arrangement of the depending tubes is such as to obtain the bestcooling effect at a mini mum resistance toward the flow of mercuryvapor.

From a consideration of Fig. 2, it will be readily seen that therelative amount of non-condensable gases increases along the path of themercury vapor, reaching a maximum value at points where the finalcondensation takes place. The increasing content of air and othernoncondensables in the mercury vapor causes an increased blanketing ofthe tubes l3 and thereby reduces considerably the heat transfer throughthese tubes. To reduce the blanketing of the tubes in order to increasethe heat transfer, I provide in accordance with my invention means forextracting non-condensable gases wherever the amount of these gasesreaches a certain value. Preferably, I provide an air-extracting tubeextending over a substantial area of minimum heat concentration due toblanketing of the tubes by the non-condensable gases. In the type ofcondenser shown in the drawing the region of minimum heat concentrationis considerably spaced from the outer condenser wall. It is locatedintermediate the center of the cylindrical condenser casing and the wallportion of the casing opposite the inlet opening [4. In the presentinstance I have shown an extraction tube l 9 having a plurality ofopenings through which the non-condensable gases are withdrawn. The tubei 9, as pointed out above, is located in a region of minimum heatconcentration and in the type of condenser shown in the drawing issurrounded by or interspaced between cooling tubes. Its upper end isconnected to the bottom 2| of an extraction chamber 22 having a V-shapedwall 23 fastened to the lower tank or casing I0 by welds 24. Thenon-condensable gases are removed from the chamber 22 by any suitablemeans through an opening 25 in the outer tank or casing l0.

It is desirable to extract air and non-condensable gases at a uniformrate along the entire length of the extraction tube. To this end Iprovide the tube with a plurality of openings having an opening area perunit tube length decreasing in the direction of the tube outlet, thatis, the opening area over a unit length near the bottom of the tube(Fig. l) is larger than over a unit length near the top or discharge endthereof. The larger opening area near the bottom causes a somewhathigher pressure to exist within the lower portion of the extraction tubethan within the upper portion thereof, resulting in flow of gases fromthe bottom portion of the tube towards the upper portion, that is,towards the discharge end thereof.

Referring now to Fig. 3, where I have shown a modification of myinvention, the condenser boiler comprises a lower tank and an upper tank3| corresponding to .tanks l0 and H respectively of Fig. 1. The lowertank has an inlet opening 32 for mercury vapor to be condensed and itsbottom is connected to a sump 33 having a conduit 34 for dischargingcondensed mercury. The upper tank 3| has an inlet opening 35 throughwhich water is conducted into .the tank and a conduit 36 for dischargingsteam. A plurality of depending dead-end tubes 3'! projecting into thelower tank 38 are connected to the upper tank 3| for receiving watertherefrom, the water being at least partly evaporated in the tubes andexpelled into the upper tank. A tube or channel 38 corresponding to thetube I9 of Fig. l is provided in the lower tank 30, extending over aconsiderable region of minimum heat concentration, that is, a region inwhich the content of non-condensable gases in the mercury vapor hasreached a maximum value. In the present instance the tube 38 has aclosed upper end and projects through the bottom of the lower tank 30.The tube has a plurality of openings 39 which are more closely spaced atthe upper end of the tube than near the lower tube portion in order toobtain uniform extraction along the tube. In the present instance I haveshown means for removing mercury vapor which may be carried along by thenon-condensable gases into the tube 38. This means comprises anauxiliary condenser 40 having an outer casing 4| forming two headers 42and 43. The headers are connected by a plurality of cooling tubes 44. Alower portion of the tank 4| is connected to a sump 45 having an outlet46 for non-condensable gases and a discharge conduit 41 for mercury. Theheaders 42 and 43 are connected to conduits 48 and 49 respectively forreceiving and discharging water, the tube 49 being connected to theinlet opening 35 of the upper tank 3|. During operation, mercury vapor,as it flows through the inlet 32 of the lower tank across the dependingtubes 31, is condensed, the condensate being discharged through the sump33 and its discharge conduit 34. The non-condensable gases and a certainamount of mercury vapor is withdrawn from the lower tank 30 through theextraction tube 38 and flows into the auxiliary condenser. Water isconducted through the conduit 48 to the header 42 of the auxiliarycondenser, whence it flows through the cooling tubes 44 into theright-hand header 43 of the auxiliary condenser. From the header 43 thepreheated water is conducted through conduit 49 into the upper tank 3|and its tubes 31 in which it is evaporated to be finally dischargedthrough the conduit 36. The mixture of noncondensable gases and mercuryvapor discharged from the extraction conduit or tube 38 flows across thetubes 44 of the auxiliary condenser whereby the mercury condenses andcollects in the sump 45 whence it is withdrawn through the conduit 4'1,the non-condensable gases being removed by any suitable means, such aspumps or the like (not shown), through the conduit 46.

During operation of condensers of the type described above, I have foundthat the non-condensables have a tendency to flow partly towards theoutlet conduit for the condensate, in which case they are dischargedpartly together with the condensate and in the case of a mercury powerplant flow into the boiler. The presence of noncondensables in the formof air in the boiler is undesirable because air causes oxidation of theboiler walls which reduces considerably the heat transfer from thesewalls and consequently the boiler output, moreover endangers theoperation of the boiler in that oxidized boiler surfaces lead to hotspots.

In accordance with my invention I provide two means for reducing theflow of non-condensables into the outlet for the condensate. The firstmeans consists in a particular location of the outlet conduit forcondensates and a special relation between the location of this outletand the location of the air removal means. As shown in Fig. l of thedrawing, the sump l5 forming an outlet for the condensate isconsiderably spaced from the air removal conduit l9. More specifically,the sump l5, that is, the outlet conduit for the condensate, isconnected to a region of the condenser in which the heat concentrationis a maximum, whereas the air removal conduit I 9, as explained above,is disposed in a region in which the heat concentration is a minimum.From another viewpoint, the discharge conduit for condensate isconnected to a region of the condenser in which the partial pressure ofcondensables, in the present instance mercury, is a maximum, that isclose to the opening l4 for admitting vapor to the condenser, whereasthe air removal means is disposed in a region in which the partialpressure of the condensables is a minimum and the partial pressure ofthe non-condensables a maximum, in the present instance, at aconsiderable distance away from the inlet I4 for admitting vapor to thecondenser. However, it is to be noted that this considerable distancebetween the inlet I4 and the air removal conduit I9 is less than thediameter of the tank because the location of the region of maximumpartial air pressure is not diametrically opposite the inlet I4. Thesecond means for preventing flow of noncondensables into the dischargeconduit for condensate comprises the provision of a deflector or likeauxiliary means for creating an artificial draft from the region towhich the discharge conduit for condensate is connected to the region inwhich the air removal conduit is disposed. As shown in Fig. 1, thismeans comprises a deflector 5!! suitably fastened to the wall of thecondenser for deflecting a portion of the vapor flowing into the inlet Mtowards the bottom of the condenser. The deflected vapor flows acrossthe connection of the casing with the sump I5 towards the air removalconduit I9. The direction of flow is indicated by an arrow 5!. Thus theprovision of the deflector 50 causes the creation of an artificial draftfrom the inlet I4 across the connection with the sump I5 towards the airremoval conduit I9. This draft reduces or prevents the formation of adraft in opposite direction. The bottom of the casing ID, as shown inthe drawing, forms a channel inclined towards the left with the sump I 5connected near the left-hand end or lowest portion of this channel.

The arrangement for preventing the flow of non-condensables from theregion of minimum heat concentration into the discharge conduit forcondensate is similar in Fig. 3 but instead of a deflector I provide inFig. 3 means including a conduit 52 for extracting vapor from thecondenser inlet 32 and discharging vapor across the inlet sump 33 in thedirection of the air removal conduit 38. The direction of flow acrossthe connection of the discharge for condensate is indicated by an arrow53. As explained before, the discharge conduit for condensate isconnected to a region in which the partial pressure of noncondensablesis a minimum, whereas the air removal conduit 38 is disposed in a regionin which the partial pressure of the non-condensables is a maximum andthe partial pressure of the condensables a minimum.

The arrangement shown in Fig. 4 includes a tank 55 corresponding to thetank I 0 of Fig. 1. The tank has an inlet 56 and a plurality of coolingtubes 51 corresponding to the tubes I3 of Fig. 1. Means including aperforated conduit58 corresponding tothe conduit I9 of Fig. 1 areprovided for extracting non-condensable gases. The conduit 58 isinterspaced between the cooling tubes 51 and disposed in a region inwhich the partial pressure of the non-condensable gases including airreaches a maximum. A sump representing in substance a conduit 59 fordischarging condensate mercury is connected to a central portion of thebottom of the tank 55. The arrangement shown in Fig. 4 is provided inaccordance with my invention with an air removal conduit disposed in aregion of maximum partial pressure of air and other non-condensablegases as is the case in the arrangement of Figs. 1 to 3. In contrast tothe latter arrangements the condensate discharge means is not connectedto a portion of the tank near the inlet for vapor to be condensed, thatis in a region in which the partial pressure of the non-condensablegases is a minimum. Whereas my invention may be used in the form shownin Fig. 4, I prefer the arrangements shown in Figs. 1 to 3.

Having described the method of operation of my invention, together withthe apparatus. which I now consider to represent the best embodimentsthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An elastic fluid surface condenser including a tank having an inletfor elastic fluid to be condensed and an outlet for condensate, coolingmeans including a plurality of tubes projecting into the tank, and meansfor extracting air and other non-condensable gases from the tank, saidmeans comprising a tube with a plurality of openings extending over asubstantial portion of the region of minimum heat concentration in thetank, the opening area of said openings per unit tube length beingreduced towards the outlet of the tube to cause uniform extraction alongthe entire length of the tube.

2. An elastic fluid surface condenser including means comprising aperforated conduit disposed within the condenser for extracting air andother non-condensable gases, a conduit connected to the condenser fordischarging condensate, and means. for creating an artificial draftacross the connection of said last named conduit with the condensertowards the perforated conduit of the air removing means.

3. An elastic fluid surface condenser including means for extracting airand other non-condon sable gases from the condenser, said means beingdisposed in a region of minimum heat concentration, a. conduit connectedto the condenser for discharging condensate, and means including adeflector for causing a draft from the connection of the condenser withsaid conduit towards the air removal means.

BEVIS P. COULSON, JR.

